A simple 12 to 220 circuit. High voltage and more. Connecting a laptop to a car

Over the many years after the advent of electricity, we finally got used to the 220 network, that any device can work from it. We want to take various household appliances with us on trips or on vacation, but in a car there are only 12 or 24. To solve this problem, it is best to use a voltage converter from 12 to 220 volts. Thanks to modern element base and PWM controllers, such a unit has become miniature and lightweight.

The second common name is “r”. Accordingly, it may be called differently in an online store, and it is not always easy to find.

As always, the Chinese lure us with low prices and high power of 12 to 220 inverters. I’ll tell you about this separately; you’re unlikely to be interested in Chinese watts, which sometimes have one extra zero.

1. Application
2. Specifications
3. Power
4. Cooling
5. Example characteristics
6. Typical power consumption
7. Additional protection
8. Connection in the car
9. How to make it yourself
10. Connecting a laptop to a car
11. Prices for converters

Application

DC-AC voltage inverters are widely used in areas without electrification. From a standard 12V battery you can get household 220V. The shape of the electrical current at the output slightly limits the application; not all electrical devices can tolerate an almost rectangular sine wave.

By the number of watts at the output there are mainly:

automotive 100W, 300W, 500 Watt;
powerful stationary 2000W, 3000W, 5000W, 10000W.

By design they are divided into:

for automobiles;
stationary;
compact.

I will consider a converter from 12 to 220 in a car to use power for LED lighting, since the entire site is dedicated to this. But all this applies to any household appliance powered by a 220V network.

When going on a picnic or to a remote dacha, it may be necessary to illuminate the room or place where you will spend the night. The easiest way is to connect LED lamp or a lamp for the home into a car inverter 12 220v. This, of course, is not very optimal from the point of view of economical energy consumption of a car battery; efficiency decreases with increasing load. The light bulb also contains a PWM driver to power the LEDs.

A stationary 12 V 220 inverter with pure sine wave is indispensable when using the energy of solar panels or wind turbines. Initially, such generators produce 12V, 24V, 36V, which can be directly accumulated.

Compact models can be powered from 12V to 50V and are more unpretentious in choosing a power source. In the car version they look like a large charger with a socket.

Specifications

All DC - AC current converters with 12 to 220 output have standard parameters, frequency 50 Hertz and 220V. They match the parameters on our home network and are compatible with almost all home devices.

Main parameters:

rated power;
coefficient useful action;
active or passive cooling;
energy consumption per Idling;
maximum current consumption at the input;
supply voltage;
protection against short circuit and overheating;
type of sinusoid at the output.

All modern converters are structurally implemented on pulse controllers, which provide high efficiency. This value can reach 95%; the remaining 5% of energy will be dissipated by the device itself, due to which it heats up.

The most affordable models have a modified sine wave output, rectangular in shape. The expensive ones have a “pure sine wave”, as smooth as a regular home outlet.

Some electrical appliances consume twice as much energy when turned on. For example, a 750W household drill will not be able to start from a 1000W inverter. Peak short-term power may not be enough to start the engine. The solution to this problem is to use electrical appliances with soft start.

Power

The real power of cheap DC-AC converters from 12 to 220 can be 2 - 3 times lower. Online stores and manufacturers use Chinese marketing to increase sales. Largely indicate the short-term peak power at which the device can operate for 5 minutes until it turns off due to overheating and overload.

For your home, you can safely buy stationary ones for 2000 W, 3000 W, 5000 W, there will always be something to load it with. Industrial ones are already rated at 10,000 W, 15,000 W and higher, designed for power supply of power tools. For passenger cars 100W, 300W, 500 Watt, 2000W is enough. If more, then serious preparation of transport is required.

When choosing, check how the power is indicated, rated long-term or short-term. When calculating the expected load, make a margin of 20% so as not to operate the converter beyond its limits, this will significantly extend its life. The expensive ones have a reserve, the cheap ones, on the contrary, are slightly short of the norm.

The connection is best done by specialists; the current from the battery for a 500W car inverter will be about 50A. If you are careless, you can burn wires and much more. It is better to play it safe and install an additional fuse or protection system. Jeepers install a separate mass shutdown button. I am a supporter of maximum safety; I have personally experienced all types of exposure to electricity, even when a screwdriver melts in my hands.

Cooling

Passive with aluminum fins

Heating depends on full power inverter and connected load. The aluminum body of the device is used as a cooling system. When the power is high, a fan is installed, due to which the air circulates inside. Active cooling does not work constantly, only when the case temperature exceeds the set temperature and the temperature sensor turns on the fan.

Automobile transport and any other are exposed to strong dust. Therefore, under heavy load, the fan may simply not turn on because it is clogged with dust.

Active cooling with fan

Example characteristics

As an illustrative example, let's look at the typical parameters of a conventional booster.

1. Rated operating power is 1000W, it can be used for any amount of time.

2. Maximum 2000W, only for a short period of time 5-10 minutes, some devices at the start consume 2 times more.

3. No-load current 1A, power consumption of the voltage converter itself from the battery without load. At 12V this would be 12 watts per hour.

4. Signal shape, modified sinusoid - rectangular current oscillations, all cheap boosters give only this shape.

5. Input voltage is 11-15V, if these values are exceeded, the protection will work and everything will turn off.

6. Output voltage 220V ±10%. The indicator depends on the load on the inverter and its quality. Typically, electronics are powered to withstand power changes within these limits.

7. Current frequency 50Hz, oscillation frequency per second.

8. Efficiency 94%, average efficiency. The remaining 6% is consumed by the device itself, due to which it heats up. A good efficiency is considered to be 90%.

Typical Power Consumption

The table shows the minimum energy consumption for popular household appliances. To find out the number of watts for a specific device, look at the number of watts on its power supply or look on the case. If you only know the markings and model name, then you can always google the characteristics. It would be most accurate to measure it with a wattmeter at home to find out the exact real indicators, which greatly depend on the operating mode.

Additional protection

Good model with indicators

A good 12 to 220 voltage converter should have protection against short circuit, overload and overheating. There must be a fuse in the device itself. The power of connected devices may vary, and children may accidentally connect the iron. To prevent the inverter from burning out, the overload protection must turn it off in a timely manner. A short circuit causes great strength current, which instantly heats the wires and they ignite. The protection unit must turn off the inverter output and not turn it on while there is a short circuit.

In high-quality models, the unit is protected from wrong polarity, too low and too high input voltage. Additional indicators and built-in voltmeters will show the current status and help identify a malfunction in advance.

Filling and design

The presence of thermal protection can be determined by the presence of a temperature sensor on the radiator for cooling the power transistors. This sensor turns on the fan when the temperature of the cooling system exceeds the permissible temperature.

Connection in car

Most often they are connected in cars; due to negligence, many have burned more than one fuse in the car’s electrical protection unit. The cigarette lighter has a limitation on the power of the connected load; you can charge your smartphone and tablet without problems. In all cars, the cigarette lighter is protected by a fuse of about 15 Amps against short circuits. It's about 180W. In the operating instructions, the manufacturer writes that there is no need to connect a load of more than 130-150W, that is, a maximum of 12 amperes, to the cigarette lighter. If there is an overload, the fuse will blow and everything will shut down. If this happens, you can temporarily take a fuse from a secondary electrical system, such as rear power windows or fog lights.

Only thick wires or good crocodiles

A powerful 12V load can only be connected directly to the battery or a separate thick wiring can be made into the car interior. Wires must not touch moving parts power unit and other mechanisms under the hood. Must have protection against abrasion and short circuit to ground. I encountered this myself when, right on the highway, all the instruments in the car suddenly went out.

Do not use cigarette lighter to crocodile adapters. They are assembled only by crimping, without soldering. Avoid any poor contact on the power lines, this will cause these areas to heat up.

How to make it yourself

Many will be interested in assembling a voltage converter from 12 to 220 with their own hands. To save my time, I prefer to use ready-made blocks or improvised devices. There are good circuits on the Internet for 2000, 2500 and 3000 W; they differ mainly in the number of power transistors at the output.

About 10 varieties of ready-made high-voltage modules are sold on Ebay and Aliexpress. From the simplest to high-quality ones with a cooler on the radiator. All that remains is to add wires and terminals, install a socket and additional protection.

Old UPS

But the most the best option Making a 12V 220 inverter with your own hands involves using a UPS uninterruptible power supply. This is a completely finished device; advanced models are equipped with screens and indicators. All that remains is to bring the 12 volt cable out. The UPS has basic types of protection; there are from 1 to 6 sockets on the case.

An old UPS costs 100-300 rubles, sometimes they are given away for free, I had 3 of them lying around. It’s easier and faster to find them on Avito, they are very common good models at fabulous prices.

Connecting a laptop to a car

We will separately consider connecting to the cigarette lighter of a laptop with a 19V power supply. It is not rational to use a 220V car inverter; you will have to make 220V from 12V and then 19V. Too much energy will be spent on transformation. The best option is to use a boost converter from 12 to 19V.

I bought a universal block for 250 rubles along with delivery on Aliexpress. In Russian stores they ask too much for it, but you can search on Avito at affordable price. I tested it with my laptop, it holds current up to 4A, the number of volts does not drop under load, heating is normal.

XL4016

Cheap Chinese blocks, of course, have real parameters lower than stated, but you can always refine the design and element base.

Converter prices

Russians love to stock up on small electronics at the Chinese Aliexpress bazaar. Due to the nature of my work, I constantly monitor prices on Aliexpress and compare them with Russian prices. As of October 2016, buying on Aliexpress is not profitable due to the dollar exchange rate. You can buy it cheaper and better in Russia, and you will also receive a guarantee and the possibility of exchange within 2 weeks.

The Chinese love to overcharge specifications, because 99% of you will not check compliance with the promised parameters. And the remaining 1% will require a small compensation for deception on the part of the seller. According to the experience of colleagues, the 3000W promised by the Chinese can be safely divided by 3, and you will get real long-term power.

If you read a review about a Chinese converter from 12 to 220, where they are happy with it and write that it works well, do not rush to go and buy from the link. They are produced by different factories, the filling can be different even within the same batch. Their quality control is low and the defect rate is relatively high. Reviews are written mainly by people who bought it recently and are using it for the first time. That is, the objectivity of the opinion is very low, believe only the results of measurements and tests.

This converter is designed to receive 220V/50Hz rectangular voltage from a 12V battery. Power from 150 to 300W, depending on the components used.

The circuit is a push-pull push-pull converter. The CD4047 chip contains a master pulse generator that controls field-effect transistors. They operate in key mode alternately, that is, only one of them is open at any given time. If for some reason both keys open, then short circuit(short circuit) and both transistors will burn out. This can happen if management is incorrect.

The transformer is taken from an uninterruptible power supply, it is 250-300W. The primary winding has a middle point, to which we connect “+” from the power source. Using a multimeter, we measure the resistance of the secondary windings and find those 2 taps between which there is the highest resistance. In my case it is 17 ohms. This is the 220V output winding. The rest of the conclusions can be nibbled away.

I drew a printed circuit board. I recommend checking all parts before assembly. It is advisable to select transistors with similar parameters. The frequency-setting capacitor must have low leakage and small tolerance. All this can be done with a transistor tester.

Any N-channel field devices with a voltage above 60V and a current of 35A (for example, IRFZ40, 44, 48, IRF3205). The circuit can also work with bipolar transistors, but the power will be much less. Resistors in the gate circuit from 10 to 100 Ohms (preferably 22 - 47 Ohms) 0.25 W. The ratings of the frequency-setting circuit are designed for 50Hz.

A correctly assembled inverter will work immediately, but the first time you turn it on, you should be on the safe side. Instead of a fuse, we install a powerful 5-10 Ohm resistor, or a 12V/5W light bulb, so that in case of problems we do not burn out the transistors. During normal operation of the inverter at idle (idle), the transformer makes a peculiar sound and the field workers do not heat up at all. If everything is so, then remove the resistor and supply power through the fuse.

Consumption at XX is from 150 to 300 mA depending on your power source and transformer. Next, we measure the output voltage with a multimeter (in the range of 750V AC voltage). In my case it is from 210 to 260V, because... the output is not stabilized. We connect the load, for example a 60W light bulb, for no more than 10 seconds, because the field workers are not yet on the radiators. They should warm up a little, but about the same. If the heating is not the same, then you need to look for the reason.

Although the power “+” is connected to the midpoint of the transformer, to turn on the inverter, a low-current “+” must be applied to the board to start the generator. A low-power button is suitable for this.

The inverter is assembled in a housing from a computer power supply. I have transistors installed on separate radiators. When installing on a common heat sink, do not forget to insulate the transistor housings. The power buses of the transformer go directly to the radiators, so they must be isolated from the general housing.

The cooler is connected directly to 12V.

By connecting an energy meter to the output, you can check the output data. If the frequency is different from 50Hz, it can be adjusted with multi-turn resistor R4.

The main disadvantage of this circuit is that there is no short circuit protection, so I added a 1A fuse at the output.

Most modern household appliances operate in the voltage range 90 - 280V. My inverter has a range from 210 to 260V. If you get an output higher than 300V, then in addition to the load, you should also connect a 25W light bulb, which will reduce the output voltage. Devices with commutator motors and with iron transformers they can also work from an inverter with rectangular pulses at the output, but they will heat up 2 times more. But it is not recommended to power asynchronous motors from it.

Buying a ready-made device will not be a problem– in auto stores you can find (pulse voltage converters) of various powers and prices.

However, the price of such a medium-power device (300-500 W) is several thousand rubles, and the reliability of many Chinese inverters is quite controversial. Making a simple converter with your own hands is not only a way to significantly save money, but also an opportunity to improve your knowledge in electronics. In case of failure, repairing a homemade circuit will be much easier.

Simple pulse converter

The circuit of this device is very simple, and most parts can be removed from an unnecessary computer power supply. Of course, it also has a noticeable drawback - the 220 volt voltage obtained at the output of the transformer is far from sinusoidal in shape and has a frequency significantly higher than the accepted 50 Hz. Electric motors or sensitive electronics must not be connected directly to it.

In order to be able to connect to this inverter containing impulse blocks power supply to equipment (for example, a laptop power supply), an interesting solution was used - A rectifier with smoothing capacitors is installed at the output of the transformer. True, the connected adapter can only work in one position of the socket, when the polarity of the output voltage coincides with the direction of the rectifier built into the adapter. Simple consumers such as incandescent lamps or a soldering iron can be connected directly to the output of transformer TR1.

The basis of the above circuit is the TL494 PWM controller, the most common in such devices. The operating frequency of the converter is set by resistor R1 and capacitor C2; their values can be taken slightly different from those indicated without noticeable changes in the operation of the circuit.

For greater efficiency, the converter circuit includes two arms on power field-effect transistors Q1 and Q2. These transistors must be placed on aluminum radiators; if you intend to use a common radiator, install the transistors through insulating spacers. Instead of the IRFZ44 indicated in the diagram, you can use IRFZ46 or IRFZ48 that are similar in parameters.

The output choke is wound on a ferrite ring from the choke, also removed from the computer power supply. The primary winding is wound with a wire with a diameter of 0.6 mm and has 10 turns with a tap from the middle. A secondary winding containing 80 turns is wound on top of it. You can also take an output transformer from a broken uninterruptible power supply.

Read also: Review of wood-burning electric generators

Instead of high-frequency diodes D1 and D2, you can take diodes of types FR107, FR207.

Since the circuit is very simple, once turned on and installed correctly, it will start working immediately and will not require any configuration. It will be able to supply a current of up to 2.5 A to the load, but the optimal operating mode will be a current of no more than 1.5 A - and this is more than 300 W of power.

Ready-made inverter of such power would cost about three to four thousand rubles.

This scheme is made with domestic components and is quite old, but this does not make it any less effective. Its main advantage is that it produces a complete alternating current with a voltage of 220 volts and a frequency of 50 Hz.

Here the oscillation generator is made on the K561TM2 microcircuit, which is a dual D-trigger. It is a complete analogue of the foreign CD4013 microcircuit and can be replaced with it without changes in the circuit.

The converter also has two power arms on bipolar transistors KT827A. Their main drawback compared to modern field ones is their higher resistance in the open state, which is why they heat up more for the same switched power.

Since the inverter operates at low frequency, the transformer must have a powerful steel core. The author of the diagram suggests using the common Soviet network transformer TS-180.

Like other inverters based on simple PWM circuits, this converter has an output voltage waveform quite different from the sinusoidal one, but this is somewhat smoothed out by the large inductance of the transformer windings and the output capacitor C7. Also, because of this, the transformer may emit a noticeable hum during operation - this is not a sign of a circuit malfunction.

Simple transistor inverter

This converter works on the same principle as the circuits listed above, but the generator rectangular pulses(multivibrator) it is built on bipolar transistors.

The peculiarity of this circuit is that it remains operational even on a heavily discharged battery: the input voltage range is 3.5...18 volts. But, since it does not have any stabilization of the output voltage, when the battery is discharged, the load voltage will simultaneously drop proportionally.

Since this circuit is also low-frequency, a transformer will be required similar to that used in the inverter based on K561TM2.

Improvements to inverter circuits

The devices presented in the article are extremely simple and have a number of functions. cannot compare with factory analogues. To improve their characteristics, you can resort to simple modifications, which will also allow you to better understand the principles of operation of pulse converters.

Read also: Let's make an electric generator with our own hands

Increased power output

All described devices operate on the same principle: through a key element (arm output transistor), the primary winding of the transformer is connected to the power input for a time specified by the frequency and duty cycle of the master oscillator. In this case, magnetic field pulses are generated, exciting common-mode pulses in the secondary winding of the transformer with a voltage equal to the voltage in the primary winding multiplied by the ratio of the number of turns in the windings.

Therefore, the current flowing through the output transistor is equal to the load current multiplied by the inverse turns ratio (transformation ratio). It is the maximum current that the transistor can pass through itself that determines the maximum power of the converter.

There are two ways to increase the power of the inverter: either use a more powerful transistor, or use parallel connection of several less powerful ones. powerful transistors in one shoulder. For a homemade converter, the second method is preferable, since it not only allows you to use cheaper parts, but also preserves the functionality of the converter if one of the transistors fails. In the absence of built-in overload protection, such a solution will significantly increase the reliability of a homemade device. The heating of the transistors will also decrease when they operate at the same load.

Using the last diagram as an example, it will look like this:

Automatic shutdown when battery is low

The absence in the converter circuit of a device that automatically turns it off when the supply voltage drops critically, can seriously let you down, if you leave such an inverter connected to the car battery. Supplementing a homemade inverter with automatic control will be extremely useful.

The simplest automatic load switch can be made from a car relay:

As you know, each relay has a certain voltage at which its contacts close. By selecting the resistance of resistor R1 (it will be about 10% of the resistance of the relay winding) you adjust the moment when the relay opens its contacts and stops supplying current to the inverter.

EXAMPLE: Let's take a relay with an operating voltage (U p) 9 volts and winding resistance (R o) 330 ohm. So that it works at a voltage above 11 volts (U min), a resistor with resistance must be connected in series with the windingR n, calculated from the condition of equalityU r /R o =(U min —U p)/R n. In our case, we will need a 73 ohm resistor, the nearest standard value is 68 ohms.

Of course, this device is extremely primitive and is more of a workout for the mind. For more stable operation, it needs to be supplemented with a simple control circuit that maintains the shutdown threshold much more accurately:

Read also: We are talking about 10 kW voltage stabilizers for the home

The response threshold is adjusted by selecting resistor R3.

We invite you to watch a video on the topic

Inverter fault detection

Listed simple circuits have two most common faults - either there is no voltage at the transformer output, or it is too low.

A car voltage inverter can sometimes be incredibly useful, but most of the products in stores either suffer from poor quality or are unsatisfactory in terms of power, and are not cheap. But the inverter circuit consists of the simplest parts, so we offer instructions for assembling a voltage converter with your own hands.

Inverter housing

The first thing to consider is the electricity conversion losses released in the form of heat on the circuit switches. On average, this value is 2-5% of the rated power of the device, but this figure tends to increase due to improper selection or aging of components.

Heat removal from semiconductor elements is of key importance: transistors are very sensitive to overheating and this is expressed in the rapid degradation of the latter and, probably, their complete failure. For this reason, the base for the case should be a heat sink - an aluminum radiator.

For radiator profiles, a regular “comb” with a width of 80-120 mm and a length of about 300-400 mm is suitable. screens are attached to the flat part of the profile with screws field effect transistors- metal spots on their back surface. But this is not all simple: there should be no electrical contact between the screens of all transistors in the circuit, so the radiator and fastenings are insulated with mica films and cardboard washers, while a thermal interface is applied to both sides of the dielectric spacer with metal-containing paste.

We determine the load and purchase components

It is extremely important to understand why an inverter is not just a voltage transformer, and also why there is such a diverse range of such devices. First of all, remember that by connecting a transformer to a DC source, you will not get anything at the output: the current in the battery does not change polarity, accordingly, the phenomenon of electromagnetic induction in the transformer is absent as such.

The first part of the inverter circuit is an input multivibrator that simulates network oscillations to perform the transformation. It is usually assembled on two bipolar transistors capable of driving power switches (for example, IRFZ44, IRF1010NPBF or more powerful - IRF1404ZPBF), for which the most important parameter is the maximum permissible current. It can reach several hundred amps, but in general you just need to multiply the current by the battery voltage to get an approximate number of watts of power output without taking into account losses.

A simple converter based on a multivibrator and power field switches IRFZ44

The operating frequency of the multivibrator is not constant; calculating and stabilizing it is a waste of time. Instead, the current at the output of the transformer is converted back to DC using a diode bridge. Such an inverter can be suitable for powering purely active loads - incandescent lamps or electric heaters, stoves.

Based on the obtained base, you can assemble other circuits that differ in the frequency and purity of the output signal. It is easier to select components for the high-voltage part of the circuit: the currents here are not so high, in some cases the output multivibrator and filter assembly can be replaced with a pair of microcircuits with appropriate wiring. Electrolytic capacitors should be used for the load network, and for circuits with low level signal - mica.

Option of a converter with a frequency generator based on K561TM2 microcircuits in the primary circuit

It is also worth noting that to increase the final power it is not at all necessary to purchase more powerful and heat-resistant components of the primary multivibrator. The problem can be solved by increasing the number of converter circuits connected in parallel, but each of them will require its own transformer.

Option with parallel connection of circuits

The struggle for a sine wave - we analyze typical circuits

Voltage inverters are used everywhere today, both by motorists who want to use household appliances away from home, and by residents of autonomous homes powered by solar energy. And in general, we can say that the complexity of the converter device directly determines the width of the range of current collectors that can be connected to it.

Unfortunately, pure “sine” is present only in the main power supply network; it is very, very difficult to achieve conversion of direct current into it. But in most cases this is not required. To connect electric motors(from a drill to a coffee grinder), a pulsating current with a frequency of 50 to 100 hertz without smoothing is sufficient.

ESL, LED bulbs and all kinds of current generators (power supplies, chargers) are more critical to the choice of frequency, since their operating circuit is based on 50 Hz. In such cases, microcircuits called a pulse generator should be included in the secondary vibrator. They can switch a small load directly, or act as a “conductor” for a series of power switches in the inverter output circuit.

But even such a cunning plan will not work if you plan to use an inverter to provide stable power to networks with a mass of heterogeneous consumers, including asynchronous electrical machines. Here, pure “sine” is very important and only frequency converters with digital signal control can implement this.

Transformer: we’ll select it or do it ourselves

To assemble the inverter, we only need one circuit element that performs the transformation low voltage to high. You can use transformers from power supplies of personal computers and old UPSs; their windings are designed to transform 12/24-250 V and back, all that remains is to correctly determine the conclusions.

Still, it’s better to wind the transformer with your own hands, since ferrite rings make it possible to do it yourself and with any parameters. Ferrite has excellent electromagnetic conductivity, which means that transformation losses will be minimal even if the wire is wound manually and not tightly. In addition, you can easily calculate the required number of turns and wire thickness using calculators available on the Internet.

Before winding, the core ring needs to be prepared - remove the sharp edges with a file and wrap tightly with an insulator - fiberglass impregnated with epoxy glue. Next comes the winding of the primary winding from thick copper wire of the calculated cross-section. After dialing the required number of turns, they must be evenly distributed over the surface of the ring at equal intervals. The winding leads are connected according to the diagram and insulated with heat shrink.

The primary winding is covered with two layers of Mylar insulating tape, then a high-voltage secondary winding and another layer of insulation are wound. Important point- you need to wind the secondary in the opposite direction, otherwise the transformer will not work. Finally, a semiconductor thermal fuse must be soldered into the gap to one of the taps, the current and response temperature of which are determined by the parameters of the secondary winding wire (the fuse body must be tightly wound to the transformer). The transformer is wrapped on top with two layers of vinyl insulation without an adhesive base, the end is secured with a tie or cyanoacrylate glue.

Installation of radio elements

All that remains is to assemble the device. Since there are not so many components in the circuit, they can be placed not on a printed circuit board, but mounted mounted to a radiator, that is, to the device body. We solder the pin legs with a solid copper wire of a sufficiently large cross-section, then the connection point is strengthened with 5-7 turns of thin transformer wire and a small amount of POS-61 solder. After the connection has cooled, it is insulated with a thin heat-shrink tube.

High power circuits with complex secondary circuitry may require a printed circuit board with transistors lined up on the edge for loose attachment to the heatsink. Fiberglass with a foil thickness of at least 50 microns is suitable for making a signet; if the coating is thinner, reinforce the low-voltage circuits with jumpers made of copper wire.

Today it’s easy to make a printed circuit board at home - the Sprint-Layout program allows you to draw clipping stencils for circuits of any complexity, including double-sided boards. The resulting image is printed by a laser printer on high-quality photo paper. Then the stencil is applied to cleaned and degreased copper, ironed, and the paper is washed away with water. The technology is called “laser ironing” (LIT) and is described on the Internet in sufficient detail.

You can etch away copper residues with ferric chloride, electrolyte, or even table salt; there are plenty of ways. After etching, the baked-on toner needs to be washed off, drill mounting holes with a 1 mm drill and go over all the tracks with a soldering iron (submerged arc) to tin the copper of the contact pads and improve the conductivity of the channels.

Everyone is accustomed to electrical appliances operating on 220V. But what if you go on a hike or some long trip, and want to take convenient household appliances with you? They will not be able to work directly from the car battery; they simply do not have enough power. This is where voltage converters from 12 to 220V can come to the rescue.

What is a converter and its essence

Thanks to technical progress, these devices have become an order of magnitude smaller and more convenient. They are easy to carry and do not take up much space. Converters are capable of raising battery voltage up to 220V. They even work from the cigarette lighter. With the help of such inverters, you can easily install lighting in a tent, as well as power your tablet, laptop, and phone from them.

PWM controllers have made such devices more advanced. The efficiency increased noticeably, and the current shape became similar to a pure sine wave. But this is only in expensive devices. It became possible to increase power to several kW.

Duration of operation depends on power and capacity batteries. Therefore, when going on a trip, it is better to limit yourself to electrical appliances with low energy consumption.

Today it is possible to buy different kinds current converters that can produce power from several hundred watts to several kW. But for tourist trips it is worth purchasing a low-power inverter.

The only obstacle to their full application is the altered current shape. From an ordinary sinusoid, it turns into an almost rectangular shape. Not all household appliances are capable of working on it.

There are 3 types of converter design:

Automotive;
Compact;
Stationary.

It is worth noting that by increasing the load, the efficiency of the converter decreases. Stationary inverters can produce a sine wave. They are convenient to use to increase voltage from wind generators and solar panels.

Converter characteristics

Before purchasing, you need to know how to choose a voltage converter. The first thing you should pay attention to is its characteristics. Often sellers give incorrect inverter performance. Indicate its peak power, at which the device can operate for several minutes, after which it turns off due to overheating. This is how the most affordable converters are advertised.

Powerful DC-AC converters increase the voltage from 12V to 220V, the current shape and frequency are equal to the usual indicators of a home network. Therefore, all devices and tools are capable of working from it.

All current converters have the following parameters:

Operating power;
Cooling type;
Energy consumption during idle operation;
Maximum input current consumption;
Protective mechanisms against short circuit and overheating;
Output current shape;
Voltage level for power supply.

The high efficiency of modern inverters is due to the pulse controllers used in the design. Almost 95% of the energy goes to the payload. The rest dissipates in the device and heats it.

In the simplest and most accessible converters, the current sinusoid changes. It becomes rectangular, and in expensive and powerful devices the current shape remains the same smooth sinusoid as in a standard outlet.

Sometimes, the power of voltage converters may not be enough to run construction tools. For example, if a drill consumes 750W, then it will not run on a 1000W inverter. To solve this problem, soft starters are sold.

Stationary type converters are used for home work. These are powerful devices capable of delivering several thousand watts. More serious converters are used in enterprises; their power amounts to tens of thousands of watts.

For cars, low-power inverters of several hundred watts are used. Because the battery is not capable of operating for a long time under heavy loads.

It is not recommended to use the converter on maximum loads. Its service life will quickly decrease. Expensive devices have a power reserve, and in the most affordable ones this figure is slightly less than what is indicated on the case.

You need to buy a device that is 20% more powerful than the expected consumption. You also need to be interested in the type of power indicated on the case. She may be:

nominal;
long-lasting;
short-term.

Cooling type

Aluminum is a metal with high thermal conductivity, and converters (especially powerful ones) can overheat when operating under heavy loads. Therefore, the cases are made from this metal.

For active system For cooling, a fan is mounted in the case. It turns on when the temperature sensor detects an increase in temperature. In car inverters, fans can become clogged with dust, which leads to poor air ventilation and overheating.

The case may have passive cooling elements. They look like aluminum fins that help dissipate heat.

Homemade converter

Radio amateurs have the opportunity to make a simple inverter using the circuit. The result is a compact device capable of powering various pocket gadgets.

There are only four transistors in the circuit. Anyone who knows how to use a soldering iron can assemble it. The resulting device is convenient to use in a car. It is capable of providing a full-fledged 220V on-board socket.